Effective heat dissipation is one of the major challenges in design of high-power optoelectronic emitters, such as VCSELs. Such devices generate large amounts of heat in the emitter active regions, resulting in high emitter junction temperatures, which tend to reduce VCSEL efficiency and lead to a reduced optical power output at a given drive current, shift the emission wavelength, degrade the quality of the laser modes, and reduce operating lifetime and reliability. In VCSEL array devices, inefficient heat dissipation causes temperature non-uniformity among emitters, leading to variations in emitter optical power and wavelength across the array.
In some designs, the VCSEL chip is thinned substantially in order to reduce the thermal resistance between the emitter junction and the heat sink on the back side of the chip. For good heat dissipation, however, the chip must be made very thin (typically on the order of 100 μm or less), which weakens its mechanical strength and causes difficulties in handling both the semiconductor substrate and the chip, and in the packaging of the chip.